What is the minimum size of a potable water service line?

The minimum size for a potable water service line is established to ensure adequate water pressure and flow for residential and commercial properties. A 3/4-inch diameter line is commonly recognized in plumbing codes as the minimum size necessary to efficiently serve standard household needs, such as providing sufficient water volume for fixtures and appliances while maintaining appropriate pressure levels.

Using a line that is too small can result in insufficient water supply, leading to inadequate performance of essential appliances like dishwashers and washing machines, and can strain plumbing systems if multiple fixtures are used simultaneously. The standards are informed by factors such as typical flow rates required for household use and the need to minimize pressure loss.

While smaller diameters like 1/2-inch can be used for individual fixtures or maintenance lines under certain conditions, they are not suitable as the primary service line for potable water in a residential setting. Sizes larger than 3/4-inch are more appropriate for larger properties with higher demands or specific applications, but for the average residential scenario, 3/4-inch remains the minimum standard for service lines supplying potable water.